The present invention relates to the removal of particles from a substrate during the manufacture of electronic packages and particularly to a system and method for removing the particles by means of inclined brushes.
In the manufacturing process of an electronic package (e.g. a SIMM or DIMM card), the mounting of a chip (device) on a substrate is usually done through soldering. This stage of the process needs to be performed in a xe2x80x9ccleanxe2x80x9d environment to avoid that unwanted particles deposited on the module obtained. For this reason the whole process is carried on in a so-called xe2x80x9cClean Roomxe2x80x9d. SIMM card, for example, are usually manufactured in panels of 10-12 pieces at a time and then cut into single cards. This cutting operation is usually done with a router-cutting machine, i.e. a machine having a rotating blade. It can happen that particles, produced during the cutting process, are deposited on the card in the form of dust. This dust is very dangerous, particularly when it is deposited on the cards gold electrical contacts and it could cause the card failure due to false electrical contacts, oxidation or even short circuits.
The removal of the particles from the card, before shipping is essential for the functionality of the final package. The presence of particles of any nature between the circuits of the substrate can be very harmful. This is particularly true when increasing reduction of dimensions in the electronic standards is considered.
What, in the past, used to be a xe2x80x9ccosmeticxe2x80x9d problem, with the reduced space between the circuit lines is becoming critical. It is likely that smaller and smaller particles will become more and more dangerous.
A technique which is normally used to remove the unwanted particles is to wash the modules with demineralised water. Another cleaning method of the prior art is by means of compressed air flow. These techniques, however do not give the assurance of a complete removal of the particles also because of the nature of these particles which are of the same material as the substrate and adhere to the card with a great strength. For this reason, a manual check with the aid of a microscope must be performed afterwards and the residual particles manually removed with brushes and scrapers.
It should be immediately evident that the above described technique is very laborious and also not completely reliable, because of the human intervention. Furthermore, the interruption of the mechanical handling of the modules for the manual checking and refinement leaves open the eventuality of contamination during the waiting times and the moving of the modules.
It is an object of the present invention to provide a technique which overcomes the above drawbacks.
According to the present invention, we provide a brushing system for removing unwanted particles from both faces of an electronic card, the system comprising:
brushing means for brushing said card faces, the brushing means including at least one couple of juxtaposed rotating brushes, each brush having the plane perpendicular to the axis of rotation of the brush forming an acute angle with the plane on which the card lies;
moving means for relatively moving the card and the brushing means, the card passing through said at least one couple of brushes.